Abstract: An air flow regulator includes a damper (14) and an air cylinder (20) operatively connected with the damper (14) to adjust a damper setting. A pressure sensor (52) indicates a pneumatic pressure in the air cylinder (20). An air pressure regulator (42) is operatively connected with the air cylinder (20) to pressurize and exhaust the air cylinder (20) responsive to an electrical input (70). The air pressure regulator (42) includes a calibration table (64) associating steady state air cylinder pressure values with regulator shut-off pressure values. Responsive to the electrical input (70) updating a steady-state air cylinder pressure value, the air pressure regulator (42) pressurizes or exhausts the air cylinder (20) until the pressure sensor (52) indicates a pressure corresponding to a regulator shut-off pressure value associated in the calibration table (64) with the updated steady-state air cylinder pressure value, whereupon the air pressure regulator (42) ceases the pressurizing or exhausting.

Abstract: An air flow regulator includes a damper (14) and an air cylinder (20) operatively connected with the damper (14) to adjust a damper setting. A pressure sensor (52) indicates a pneumatic pressure in the air cylinder (20). An air pressure regulator (42) is operatively connected with the air cylinder (20) to pressurize and exhaust the air cylinder (20) responsive to an electrical input (70). The air pressure regulator (42) includes a calibration table (64) associating steady state air cylinder pressure values with regulator shut-off pressure values. Responsive to the electrical input (70) updating a steady-state air cylinder pressure value, the air pressure regulator (42) pressurizes or exhausts the air cylinder (20) until the pressure sensor (52) indicates a pressure corresponding to a regulator shut-off pressure value associated in the calibration table (64) with the updated steady-state air cylinder pressure value, whereupon the air pressure regulator (42) ceases the pressurizing or exhausting.

Abstract: An improved security system, including a protable smart card and a host computer, eliminates the need for the computer to store individual personal identification (ID) numbers for each user seeking access to the computer. Instead, the computer stores a first encryption algorithm E.sub.1 used in converting a particular identification number (ID).sub.n into a secret code S.sub.n for that particular user. S.sub.n also exists within the memory of the smart card having been loaded into its memory at the time of issue. A challenge number C is generated by the computer and transmitted to the smart card. Within the smart card and the computer, microprocessors respond to the challenge number C, the secret code S.sub.n, and a second encryption algorithm E.sub.2 in order to generate response numbers R.sub.n and R.sub.n ' respectively. Thereafter, R.sub.n is transmitted to the computer where it is compared with R.sub.n '. A favorable comparison is necessary for gaining access to the computer.